Wireless communication method and wireless communication terminal for spatial reuse operation

ABSTRACT

The present invention relates a wireless communication method and a wireless communication terminal for supporting a spatial reuse operation of an overlapping basic service set to efficiently use a wireless resource. To this end, provided are a base wireless communication terminal including: a processor; and a communication unit, wherein the processor receives a PHY protocol data unit (PPDU) through the communication unit, determines whether the PPDU contains an intra-BSS frame or contains an inter-BSS frame based on preamble information of the PPDU, and performs either a first operation or a second operation distinct from each other according to a determination result and a wireless communication method using the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/219,937 filed on Dec. 13, 2018, which is a continuation ofInternational Patent Application No. PCT/KR2017/006211 filed on Jun. 14,2017, which claims the priority to Korean Patent Application No.10-2016-0074091 filed in the Korean Intellectual Property Office on Jun.14, 2016, and Korean Patent Application No. 10-2016-0086044 filed in theKorean Intellectual Property Office on Jul. 7, 2016, the entire contentsof which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a wireless communication method and awireless communication terminal for a spatial reuse operation, and moreparticularly, to a wireless communication method and a wirelesscommunication terminal for supporting a spatial reuse operation of anoverlapping basic service set to efficiently use a wireless resource.

BACKGROUND ART

In recent years, with supply expansion of mobile apparatuses, a wirelessLAN technology that can provide a rapid wireless Internet service to themobile apparatuses has been significantly spotlighted. The wireless LANtechnology allows mobile apparatuses including a smart phone, a smartpad, a laptop computer, a portable multimedia player, an embeddedapparatus, and the like to wirelessly access the Internet in home or acompany or a specific service providing area based on a wirelesscommunication technology in a short range.

Institute of Electrical and Electronics Engineers (IEEE) 802.11 hascommercialized or developed various technological standards since aninitial wireless LAN technology is supported using frequencies of 2.4GHz. First, the IEEE 802.11b supports a communication speed of a maximumof 11 Mbps while using frequencies of a 2.4 GHz band. IEEE 802.11a whichis commercialized after the IEEE 802.11b uses frequencies of not the 2.4GHz band but a 5 GHz band to reduce an influence by interference ascompared with the frequencies of the 2.4 GHz band which aresignificantly congested and improves the communication speed up to amaximum of 54 Mbps by using an OFDM technology. However, the IEEE802.11a has a disadvantage in that a communication distance is shorterthan the IEEE 802.11b. In addition, IEEE 802.11g uses the frequencies ofthe 2.4 GHz band similarly to the IEEE 802.11b to implement thecommunication speed of a maximum of 54 Mbps and satisfies backwardcompatibility to significantly come into the spotlight and further, issuperior to the IEEE 802.11a in terms of the communication distance.

Moreover, as a technology standard established to overcome a limitationof the communication speed which is pointed out as a weak point in awireless LAN, IEEE 802.11n has been provided. The IEEE 802.11n aims atincreasing the speed and reliability of a network and extending anoperating distance of a wireless network. In more detail, the IEEE802.11n supports a high throughput (HT) in which a data processing speedis a maximum of 540 Mbps or more and further, is based on a multipleinputs and multiple outputs (MIMO) technology in which multiple antennasare used at both sides of a transmitting unit and a receiving unit inorder to minimize a transmission error and optimize a data speed.Further, the standard can use a coding scheme that transmits multiplecopies which overlap with each other in order to increase datareliability.

As the supply of the wireless LAN is activated and further, applicationsusing the wireless LAN are diversified, the need for new wireless LANsystems for supporting a higher throughput (very high throughput (VHT))than the data processing speed supported by the IEEE 802.11n has comeinto the spotlight. Among them, IEEE 802.11ac supports a wide bandwidth(80 to 160 MHz) in the 5 GHz frequencies. The IEEE 802.11ac standard isdefined only in the 5 GHz band, but initial 11ac chipsets will supporteven operations in the 2.4 GHz band for the backward compatibility withthe existing 2.4 GHz band products. Theoretically, according to thestandard, wireless LAN speeds of multiple stations are enabled up to aminimum of 1 Gbps and a maximum single link speed is enabled up to aminimum of 500 Mbps. This is achieved by extending concepts of awireless interface accepted by 802.11n, such as a wider wirelessfrequency bandwidth (a maximum of 160 MHz), more MIMO spatial streams (amaximum of 8), multi-user MIMO, and high-density modulation (a maximumof 256 QAM). Further, as a scheme that transmits data by using a 60 GHzband instead of the existing 2.4 GHz/5 GHz, IEEE 802.11ad has beenprovided. The IEEE 802.11ad is a transmission standard that provides aspeed of a maximum of 7 Gbps by using a beamforming technology and issuitable for high bit rate moving picture streaming such as massive dataor non-compression HD video. However, since it is difficult for the 60GHz frequency band to pass through an obstacle, it is disadvantageous inthat the 60 GHz frequency band can be used only among devices in ashort-distance space.

Meanwhile, in recent years, as next-generation wireless LAN standardsafter the 802.11ac and 802.11ad, discussion for providing ahigh-efficiency and high-performance wireless LAN communicationtechnology in a high-density environment is continuously performed. Thatis, in a next-generation wireless LAN environment, communication havinghigh frequency efficiency needs to be provided indoors/outdoors underthe presence of high-density stations and access points (APs) andvarious technologies for implementing the communication are required.

DISCLOSURE Technical Problem

The present invention has an object to providehigh-efficiency/high-performance wireless LAN communication in ahigh-density environment as described above.

The present invention has an object to prevent an uplink multi-usertransmission process from being interrupted due to a spatial reuseoperation of an inter-BSS terminal.

The present invention has an object to provide a wireless communicationmethod and a wireless communication terminal in a high densityenvironment including an overlapping basic service set.

Technical Solution

In order to achieve the objects, the present invention provides awireless communication method and a wireless communication terminal asbelow.

First, an exemplary embodiment of the present invention provides a basewireless communication terminal, including a processor; and acommunication unit, wherein the processor receives a PHY protocol dataunit (PPDU) through the communication unit, determines whether the PPDUcontains an intra-BSS frame or contains an inter-BSS frame based onpreamble information of the PPDU, and performs either a first operationor a second operation distinct from each other according to adetermination result.

In addition, an exemplary embodiment of the present invention provides awireless communication method of a base wireless communication terminal,including: receiving a PHY protocol data unit (PPDU); determiningwhether the PPDU contains an intra-BSS frame or contains an inter-BSSframe based on preamble information of the PPDU; and performing either afirst operation or a second operation distinct from each other accordingto a determination result.

When the PPDU is an high efficiency (HE) multi-user (MU) PPDU, theprocessor may determine whether the PPDU contains an intra-BSS frame orcontains an inter-BSS frame based on information of a user specificfield in HE-SIG-B of the PPDU.

If an AID indicated by a user field in the HE-SIG-B contains a valuethat is not assigned in a BSS of the base wireless communicationterminal, the processor may determine that the PPDU contains aninter-BSS frame.

When the PPDU is an HE MU PPDU transmitted via an uplink, a STA-ID fieldof the user field in the HE-SIG-B of the PPDU may indicate an AID of atransmitter.

The processor may determine whether the PPDU contains an intra-BSS frameor contains an inter-BSS frame based on information of a BSS color fieldin HE-SIG-A of the PPDU.

The processor may determine whether the PPDU contains an intra-BSS frameor contains an inter-BSS frame based on at least one of information of aBSS color field in HE-SIG-A of the PPDU and information of a userspecific field in HE-SIG-B of the PPDU, and when the PPDU satisfies bothan intra-BSS condition and an inter-BSS condition, a determination basedon the user specific field may take precedence over a determinationbased on the BSS color field.

The processor may determine whether the PPDU contains an intra-BSS frameor contains an inter-BSS frame based on at least one of information of auser specific field in HE-SIG-B of the PPDU and information of a MACaddress field of a MAC frame contained in the PPDU, and when the PPDUsatisfies both an intra-BSS condition and an inter-BSS condition, adetermination based on the MAC address field may take precedence over adetermination based on the user specific field.

When a received frame is determined as an intra-BSS frame, the processormay determine whether a channel is busy based on a first CCA threshold,and when the received frame is determined as an inter-BSS frame, theprocessor may determine whether the channel is busy based on both thefirst CCA threshold and a second CCA threshold which is distinct fromthe first CCA threshold.

When a received frame is determined as an intra-BSS frame, the processormay set or update a first network allocation vector (NAV), and when thereceived frame is determined as an inter-BSS frame, the processor mayset or update a second NAV.

The second CCA threshold may have a value equal to or greater than thefirst CCA threshold.

Next, another exemplary embodiment of the present invention provides awireless communication terminal, including a processor; and acommunication unit, wherein the processor receives a PHY protocol dataunit (PPDU) through the communication unit, obtains a TXOP durationvalue from a TXOP duration field in HE-SIG-A of the PPDU, and sets orupdates a NAV based on the obtained TXOP duration value.

In addition, another exemplary embodiment of the present inventionprovides a wireless communication method of a wireless communicationterminal, including: receiving a PHY protocol data unit (PPDU) throughthe communication unit; obtaining a TXOP duration value from a TXOPduration field in HE-SIG-A of the PPDU; and setting or updating a NAVbased on the obtained TXOP duration value.

The TXOP duration field may contain a first bit field indicating alength of a TXOP and a second bit field indicating a granularity of aTXOP length.

The TXOP duration value may be determined based on a value obtained bymultiplying the length of the TXOP obtained from the first bit field andthe granularity of the TXOP length obtained from the second bit field.

Advantageous Effects

According to an embodiment of the present invention, if the receivedframe is determined as an inter-BSS frame, the spatial reuse operationcan be performed, thereby efficiently using the wireless resources.

Further, according to an embodiment of the present invention, byrestricting the spatial reuse operation in specific conditions, it ispossible to prevent interference from occurring when STAs indicated by atrigger frame perform carrier sense.

According to an embodiment of the present invention, it is possible toincrease the total resource utilization rate in the contention-basedchannel access system and improve the performance of the wireless LANsystem.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a wireless LAN system according to an embodiment ofthe present invention.

FIG. 2 illustrates a wireless LAN system according to another embodimentof the present invention.

FIG. 3 illustrates a configuration of a station according to anembodiment of the present invention.

FIG. 4 illustrates a configuration of an access point according to anembodiment of the present invention.

FIG. 5 schematically illustrates a process in which a STA and an AP seta link.

FIG. 6 illustrates an UL-MU transmission procedure according to anembodiment of the present invention.

FIG. 7 illustrates a spatial reuse operation according to an embodimentof the present invention.

FIG. 8 illustrates an embodiment of the present invention forrestricting a spatial reuse operation.

FIG. 9 illustrates another embodiment of the present invention forrestricting a spatial reuse operation.

FIG. 10 illustrates a legacy PPDU containing a trigger frame.

FIG. 11 illustrates a non-legacy PPDU containing a trigger frame.

FIG. 12 illustrates a further embodiment of the invention forrestricting a spatial reuse operation.

FIG. 13 illustrates a spatial reuse operation according to an embodimentof the present invention.

FIG. 14 illustrates an HE MU PPDU format according to an embodiment ofthe present invention.

FIG. 15 illustrates an encoding structure and transmission method of anHE-SIG-B according to an embodiment of the present invention.

FIG. 16 illustrates a method for determining an intra-BSS frame and aninter-BSS frame according to a further embodiment of the presentinvention.

FIG. 17 illustrates an embodiment for transmitting an HE MU PPDU via anuplink and setting a NAV accordingly.

FIG. 18 illustrates another embodiment of transmitting an HE MU PPDU viaan uplink.

FIG. 19 illustrates an HE PPDU format according to an embodiment of thepresent invention.

FIGS. 20 to 22 illustrate embodiments of a method of setting andinterpreting a TXOP duration field.

FIGS. 23 and 24 illustrate additional embodiments for setting andupdating a NAV based on a TXOP duration value.

DETAILED DESCRIPTION OF THE INVENTION

Terms used in the specification adopt general terms which are currentlywidely used by considering functions in the present invention, but theterms may be changed depending on an intention of those skilled in theart, customs, and emergence of new technology. Further, in a specificcase, there is a term arbitrarily selected by an applicant and in thiscase, a meaning thereof will be described in a corresponding descriptionpart of the invention. Accordingly, it should be revealed that a termused in the specification should be analyzed based on not just a name ofthe term but a substantial meaning of the term and contents throughoutthe specification.

Throughout this specification and the claims that follow, when it isdescribed that an element is “coupled” to another element, the elementmay be “directly coupled” to the other element or “electrically coupled”to the other element through a third element. Further, unless explicitlydescribed to the contrary, the word “comprise” and variations such as“comprises” or “comprising”, will be understood to imply the inclusionof stated elements but not the exclusion of any other elements.Moreover, limitations such as “or more” or “or less” based on a specificthreshold may be appropriately substituted with “more than” or “lessthan”, respectively.

This application claims priority to and the benefit of Korean PatentApplication Nos. 10-2016-0074091 and 10-2016-0086044 filed in the KoreanIntellectual Property Office and the embodiments and mentioned itemsdescribed in the respective application, which forms the basis of thepriority, shall be included in the Detailed Description of the presentapplication.

FIG. 1 is a diagram illustrating a wireless LAN system according to anembodiment of the present invention. The wireless LAN system includesone or more basic service sets (BSS) and the BSS represents a set ofapparatuses which are successfully synchronized with each other tocommunicate with each other. In general, the BSS may be classified intoan infrastructure BSS and an independent BSS (IBSS) and FIG. 1illustrates the infrastructure BSS between them.

As illustrated in FIG. 1, the infrastructure BSS (BSS1 and BSS2)includes one or more stations STA1, STA2, STA3, STA4, and STA5, accesspoints PCP/AP-1 and PCP/AP-2 which are stations providing a distributionservice, and a distribution system (DS) connecting the multiple accesspoints PCP/AP-1 and PCP/AP-2.

The station (STA) is a predetermined device including medium accesscontrol (MAC) following a regulation of an IEEE 802.11 standard and aphysical layer interface for a wireless medium, and includes both anon-access point (non-AP) station and an access point (AP) in a broadsense. Further, in the present specification, a term ‘terminal’ may beused to refer to a non-AP STA, or an AP, or to both terms. A station forwireless communication includes a processor and a communication unit andaccording to the embodiment, may further include a user interface unitand a display unit. The processor may generate a frame to be transmittedthrough a wireless network or process a frame received through thewireless network and besides, perform various processing for controllingthe station. In addition, the communication unit is functionallyconnected with the processor and transmits and receives frames throughthe wireless network for the station. According to the presentinvention, a terminal may be used as a term which includes userequipment (UE).

The access point (AP) is an entity that provides access to thedistribution system (DS) via wireless medium for the station associatedtherewith. In the infrastructure BSS, communication among non-APstations is, in principle, performed via the AP, but when a direct linkis configured, direct communication is enabled even among the non-APstations. Meanwhile, in the present invention, the AP is used as aconcept including a personal BSS coordination point (PCP) and mayinclude concepts including a centralized controller, a base station(BS), a node-B, a base transceiver system (BTS), and a site controllerin a broad sense. In the present invention, an AP may also be referredto as a base wireless communication terminal. The base wirelesscommunication terminal may be used as a term which includes an AP, abase station, an eNB (i.e. eNodeB) and a transmission point (TP) in abroad sense. In addition, the base wireless communication terminal mayinclude various types of wireless communication terminals that allocatemedium resources and perform scheduling in communication with aplurality of wireless communication terminals.

A plurality of infrastructure BSSs may be connected with each otherthrough the distribution system (DS). In this case, a plurality of BSSsconnected through the distribution system is referred to as an extendedservice set (ESS).

FIG. 2 illustrates an independent BSS which is a wireless LAN systemaccording to another embodiment of the present invention. In theembodiment of FIG. 2, duplicative description of parts, which are thesame as or correspond to the embodiment of FIG. 1, will be omitted.

Since a BSS3 illustrated in FIG. 2 is the independent BSS and does notinclude the AP, all stations STA6 and STA7 are not connected with theAP. The independent BSS is not permitted to access the distributionsystem and forms a self-contained network. In the independent BSS, therespective stations STA6 and STA7 may be directly connected with eachother.

FIG. 3 is a block diagram illustrating a configuration of a station 100according to an embodiment of the present invention. As illustrated inFIG. 3, the station 100 according to the embodiment of the presentinvention may include a processor 110, a communication unit 120, a userinterface unit 140, a display unit 150, and a memory 160.

First, the communication unit 120 transmits and receives a wirelesssignal such as a wireless LAN packet, or the like and may be embedded inthe station 100 or provided as an exterior. According to the embodiment,the communication unit 120 may include at least one communication moduleusing different frequency bands. For example, the communication unit 120may include communication modules having different frequency bands suchas 2.4 GHz, 5 GHz, and 60 GHz. According to an embodiment, the station100 may include a communication module using a frequency band of 6 GHzor more and a communication module using a frequency band of 6 GHz orless. The respective communication modules may perform wirelesscommunication with the AP or an external station according to a wirelessLAN standard of a frequency band supported by the correspondingcommunication module. The communication unit 120 may operate only onecommunication module at a time or simultaneously operate multiplecommunication modules together according to the performance andrequirements of the station 100. When the station 100 includes aplurality of communication modules, each communication module may beimplemented by independent elements or a plurality of modules may beintegrated into one chip. In an embodiment of the present invention, thecommunication unit 120 may represent a radio frequency (RF)communication module for processing an RF signal.

Next, the user interface unit 140 includes various types of input/outputmeans provided in the station 100. That is, the user interface unit 140may receive a user input by using various input means and the processor110 may control the station 100 based on the received user input.Further, the user interface unit 140 may perform output based on acommand of the processor 110 by using various output means.

Next, the display unit 150 outputs an image on a display screen. Thedisplay unit 150 may output various display objects such as contentsexecuted by the processor 110 or a user interface based on a controlcommand of the processor 110, and the like. Further, the memory 160stores a control program used in the station 100 and various resultingdata. The control program may include an access program required for thestation 100 to access the AP or the external station.

The processor 110 of the present invention may execute various commandsor programs and process data in the station 100. Further, the processor110 may control the respective units of the station 100 and control datatransmission/reception among the units. According to the embodiment ofthe present invention, the processor 110 may execute the program foraccessing the AP stored in the memory 160 and receive a communicationconfiguration message transmitted by the AP. Further, the processor 110may read information on a priority condition of the station 100 includedin the communication configuration message and request the access to theAP based on the information on the priority condition of the station100. The processor 110 of the present invention may represent a maincontrol unit of the station 100 and according to the embodiment, theprocessor 110 may represent a control unit for individually controllingsome component of the station 100, for example, the communication unit120, and the like. That is, the processor 110 may be a modem or amodulator/demodulator for modulating and demodulating wireless signalstransmitted to and received from the communication unit 120. Theprocessor 110 controls various operations of wireless signaltransmission/reception of the station 100 according to the embodiment ofthe present invention. A detailed embodiment thereof will be describedbelow.

The station 100 illustrated in FIG. 3 is a block diagram according to anembodiment of the present invention, where separate blocks areillustrated as logically distinguished elements of the device.Accordingly, the elements of the device may be mounted in a single chipor multiple chips depending on design of the device. For example, theprocessor 110 and the communication unit 120 may be implemented whilebeing integrated into a single chip or implemented as a separate chip.Further, in the embodiment of the present invention, some components ofthe station 100, for example, the user interface unit 140 and thedisplay unit 150 may be optionally provided in the station 100.

FIG. 4 is a block diagram illustrating a configuration of an AP 200according to an embodiment of the present invention. As illustrated inFIG. 4, the AP 200 according to the embodiment of the present inventionmay include a processor 210, a communication unit 220, and a memory 260.In FIG. 4, among the components of the AP 200, duplicative descriptionof parts which are the same as or correspond to the components of thestation 100 of FIG. 2 will be omitted.

Referring to FIG. 4, the AP 200 according to the present inventionincludes the communication unit 220 for operating the BSS in at leastone frequency band. As described in the embodiment of FIG. 3, thecommunication unit 220 of the AP 200 may also include a plurality ofcommunication modules using different frequency bands. That is, the AP200 according to the embodiment of the present invention may include twoor more communication modules among different frequency bands, forexample, 2.4 GHz, 5 GHz, and 60 GHz together. Preferably, the AP 200 mayinclude a communication module using a frequency band of 6 GHz or moreand a communication module using a frequency band of 6 GHz or less. Therespective communication modules may perform wireless communication withthe station according to a wireless LAN standard of a frequency bandsupported by the corresponding communication module. The communicationunit 220 may operate only one communication module at a time orsimultaneously operate multiple communication modules together accordingto the performance and requirements of the AP 200. In an embodiment ofthe present invention, the communication unit 220 may represent a radiofrequency (RF) communication module for processing an RF signal.

Next, the memory 260 stores a control program used in the AP 200 andvarious resulting data. The control program may include an accessprogram for managing the access of the station. Further, the processor210 may control the respective units of the AP 200 and control datatransmission/reception among the units. According to the embodiment ofthe present invention, the processor 210 may execute the program foraccessing the station stored in the memory 260 and transmitcommunication configuration messages for one or more stations. In thiscase, the communication configuration messages may include informationabout access priority conditions of the respective stations. Further,the processor 210 performs an access configuration according to anaccess request of the station. According to an embodiment, the processor210 may be a modem or a modulator/demodulator for modulating anddemodulating wireless signals transmitted to and received from thecommunication unit 220. The processor 210 controls various operationssuch as wireless signal transmission/reception of the AP 200 accordingto the embodiment of the present invention. A detailed embodimentthereof will be described below.

FIG. 5 is a diagram schematically illustrating a process in which a STAsets a link with an AP.

Referring to FIG. 5, the link between the STA 100 and the AP 200 is setthrough three steps of scanning, authentication, and association in abroad way. First, the scanning step is a step in which the STA 100obtains access information of BSS operated by the AP 200. A method forperforming the scanning includes a passive scanning method in which theAP 200 obtains information by using a beacon message (S101) which isperiodically transmitted and an active scanning method in which the STA100 transmits a probe request to the AP (S103) and obtains accessinformation by receiving a probe response from the AP (S105).

The STA 100 that successfully receives wireless access information inthe scanning step performs the authentication step by transmitting anauthentication request (S107 a) and receiving an authentication responsefrom the AP 200 (S107 b). After the authentication step is performed,the STA 100 performs the association step by transmitting an associationrequest (S109 a) and receiving an association response from the AP 200(S109 b). In this specification, an association basically means awireless association, but the present invention is not limited thereto,and the association may include both the wireless association and awired association in a broad sense.

Meanwhile, an 802.1X based authentication step (S111) and an IP addressobtaining step (S113) through DHCP may be additionally performed. InFIG. 5, the authentication server 300 is a server that processes 802.1Xbased authentication with the STA 100 and may be present in physicalassociation with the AP 200 or present as a separate server.

Multi-User Transmission

When using orthogonal frequency division multiple access (OFDMA) ormulti-input multi-output (MIMO), one wireless communication terminal cansimultaneously transmit data to a plurality of wireless communicationterminals. Further, one wireless communication terminal cansimultaneously receive data from a plurality of wireless communicationterminals. For example, a downlink multi-user (DL-MU) transmission inwhich an AP simultaneously transmits data to a plurality of STAs, and anuplink multi-user (UL-MU) transmission in which a plurality of STAssimultaneously transmit data to the AP may be performed.

FIG. 6 illustrates an UL-MU transmission procedure according to anembodiment of the present invention. In order to perform the UL-MUtransmission, the channel to be used and the transmission start time ofeach STA that performs uplink transmission should be adjusted. Accordingto an embodiment of the present invention, the UL-MU transmissionprocess may be managed by the AP. The UL-MU transmission may beperformed in response to a trigger frame transmitted by the AP. Thetrigger frame indicates a UL-MU transmission of one or more STAs. TheSTA indicated to perform UL-MU transmission by the trigger frametransmits a trigger-based PHY protocol data unit (PPDU) in response tothe trigger frame. In this case, the STA may transmit the trigger-basedPPDU a SIFS time after receiving the trigger frame. Further, the triggerframe may inform resource unit information, that is, channel orsubchannel information allocated to each STA for transmitting thetrigger-based PPDU. When the AP transmits a trigger frame, STAsindicated by the trigger frame transmit uplink data through eachallocated resource unit. After the uplink data transmission iscompleted, the AP transmits an ACK to STAs that have successfullytransmitted uplink data. In this case, the AP may transmit apredetermined multi-STA block ACK as an ACK for one or more STAs.

In the non-legacy wireless LAN system, a specific number, for example,26, 52, or 106 tones may be used as a resource unit (RU) for asubchannel-based access in a channel of 20 MHz band. Accordingly, thetrigger frame may indicate identification information of each STAparticipating in the UL-MU transmission and information of the allocatedresource unit. The identification information of the STA includes atleast one of an association ID (AID), a partial AID, and a MAC addressof the STA. Further, the information of the resource unit includes thesize and placement information of the resource unit.

According to an embodiment of the present invention, the trigger framemay be transmitted in various forms. According to an embodiment, thetrigger frame may be transmitted in the form of aggregated MAC protocoldata unit (A-MPDU) aggregated with other frames. When a trigger frameand another frame are aggregated to form an A-MPDU, the trigger framemay be located at the start of the corresponding A-MPDU. According toanother embodiment, the trigger frame may be transmitted on a broadcastresource unit of a high efficiency (HE) MU PPDU. In this case, thetrigger frame may not contain a user information field for a STAidentified as a recipient of other resource unit or other spatial streamof the same HE MU PPDU.

According to the embodiment of the present invention, carrier sense (CS)may be required before the STAs respond to the trigger frame. At leastone of a clear channel assessment (CCA) and a virtual carrier sense maybe used as the carrier sense before responding to the trigger frame. Thetrigger frame may indicate through a CS required subfield whethercarrier sense is required before the STAs respond to the trigger frame.If the CS required subfield of the trigger frame is set to 1, the STAconsiders the CCA state and virtual CS for a SIFS time between thetrigger frame and the trigger-based PPDU transmitted in responsethereto. In this case, the CCA to be performed may be a CCA-energydetect (ED). The STA performs the CCA-ED for one or more 20 MHz channelsincluding the resource units to which the uplink transmission of the STAis allocated. When the channel on which the CCA-ED is performed is idle,the STA transmits a trigger-based PPDU through the allocated resourceunit. However, when the channel on which the CCA-ED is performed isbusy, the STA does not transmit the trigger-based PPDU. On the otherhand, when the CS required subfield of the trigger frame is set to 0,the STA transmits the trigger-based PPDU regardless of the idle/busystate of the channel.

According to an embodiment of the present invention, a networkallocation vector (NAV) in a virtual CS may be considered to respond toa trigger frame if at least one of the following conditions is notsatisfied.

-   -   When a NAV is set by a frame of an AP that has transmitted a        trigger frame    -   When a response transmitted by a triggered STA contains an ACK        or a block ACK, and the length of the trigger-based PPDU is less        than a threshold    -   When a NAV is set by an intra-BSS frame    -   When the CS required subfield of the trigger frame is set to 0    -   Other conditions

Spatial Reuse Operation

Due to the spread of mobile devices and the spread of wirelesscommunication systems, terminals are increasingly communicating in adense environment. In particular, the number of cases where a terminalcommunicates in an environment in which a plurality of BSSs areoverlapped is increasing. When a plurality of BSSs are overlapped,communication efficiency of the terminal may be degraded due tointerference with other terminals. In particular, if a frequency band isused through a contention procedure, the terminal may not be able tosecure even a transmission opportunity due to interference with otherterminals. To solve this problem, the terminal may perform the spatialreuse (SR) operation.

More specifically, the terminal may determine whether a frame is anintra-BSS frame or an inter-BSS frame based on information foridentifying a BSS of a received frame. The information for identifying aBSS includes at least one of a BSS color, a partial BSS color, a partialAID, a STA-ID, or a MAC address. In the embodiment of the presentinvention, the non-legacy terminal may refer to a terminal that complieswith the next generation wireless LAN standard (i.e., IEEE 802.11ax).Also, the intra-BSS frame indicates a frame transmitted from a terminalbelonging to the same BSS, and the inter-BSS frame indicates a frametransmitted from a terminal belonging to an overlapping BSS (OBSS) oranother BSS.

Various conditions can be used to determine whether the received frameis an intra-BSS frame or an inter-BSS frame. If a BSS color of thereceived frame is equal to a BSS color of a BSS of the terminal, thereceived frame is determined as an intra-BSS frame. Also, if a MACaddress of the received frame is equal to a BSSID of the BSS of theterminal, the received frame is determined as an intra-BSS frame.Further, if the MAC address of the received frame is equal to one ofBSSIDs in a multiple BSSID set to which a BSSID of the BSS of theterminal belongs, the received frame is determined as an intra-BSSframe. Here, the MAC address of the received frame includes at least oneof a receiver address field, a transmitter address field, or a BSSIDfield of the frame. If the received frame does not satisfy the abovelisted conditions, the received frame may be determined as an inter-BSSframe.

Meanwhile, the determination results may be different in two or moreintra/inter-BSS determination conditions. For example, the receivedframe may be determined as an intra-BSS frame under the determinationcondition based on the BSS color, but the received frame may bedetermined as an inter-BSS frame under the determination condition basedon the MAC address. That is, the received frame may satisfy both theintra-BSS determination condition and the inter-BSS determinationcondition. In this case, the determination based on the MAC address maytake precedence over the determination based on the other condition(i.e., the BSS color). That is, in the above example, the terminal mayfinally determine the received frame as an inter-BSS frame according tothe determination condition based on the MAC address.

According to the embodiment of the present invention, the non-legacyterminal may perform different operations depending on whether thereceived frame is an intra-BSS frame. That is, when the received frameis determined as an intra-BSS frame, the terminal may perform the firstoperation. In addition, when the received frame is determined as aninter-BSS frame, the terminal may perform the second operation differentfrom the first operation. According to an embodiment, the secondoperation performed by the terminal when the received frame isdetermined as an inter-BSS frame may be the SR operation. According tothe embodiment of the present invention, the first operation and thesecond operation may be set in various ways.

According to an embodiment, the terminal may perform channel accessbased on different thresholds depending on whether the received frame isan intra-BSS frame. More specifically, when the received frame isdetermined as an intra-BSS frame, the terminal accesses the channelbased on the first CCA threshold (i.e., the first operation). That is,the terminal performs a CCA based on the first CCA threshold, anddetermines whether the channel is busy based on a result of performingthe CCA. On the other hand, when the received frame is determined as aninter-BSS frame, the terminal may access the channel based on the secondCCA threshold (i.e., the second operation, or SR operation), which isdistinct from the first CCA threshold. That is, the terminal determineswhether the channel is busy based on both the first CCA threshold andthe second CCA threshold. According to the embodiment of the presentinvention, the second CCA threshold is an OBSS PD level set fordetermining whether a channel is busy according to a received signalstrength of an inter-BSS frame. In this case, the second CCA thresholdmay have a value equal to or greater than the first CCA threshold.

According to another embodiment, the terminal may set or update adifferent network allocation vector (NAV) according to whether thereceived frame is an intra-BSS frame. More specifically, when thereceived frame is determined as an intra-BSS frame, the terminal sets orupdates the first NAV (i.e., the first operation). On the other hand, ifthe received frame is determined as an inter-BSS frame or if it is notdetermined whether the received frame is an intra-BSS frame or aninter-BSS frame, the terminal sets or updates the second NAV (i.e., thesecond operation). According to an embodiment, the first NAV may be anintra-BSS NAV and the second NAV may be a basic NAV (or a regular NAV).

FIG. 7 illustrates a spatial reuse operation according to an embodimentof the present invention. In the embodiment of FIG. 7, AP1 and STA1 areterminals of the first BSS (i.e., BSS1), and STA2 is a terminal of thesecond BSS (i.e., BSS2). AP1 transmits a trigger frame 410 for UL-MUtransmission of BSS1. In this case, it is assumed that the CS requiredsubfield of the trigger frame 410 is set to 1. STA1 of BSS1 and STA2 ofBSS2 receive the trigger frame 410. The STA2 can perform the spatialreuse operation because the received trigger frame 410 is an inter-BSSframe. However, if there is no separate constraint condition, STA2 maystart transmission of a PPDU 430 before the transmission of the triggerframe 410 is completed. If the transmission of the PPDU 430 of the STA2continues after the completion of the transmission of the trigger frame410, it may affect the carrier sense of STA1 which intends to transmit atrigger-based PPDU 420. More specifically, when the CS required subfieldof the trigger frame 410 is set to 1, STA 1 performs the CCA-ED totransmit the trigger-based PPDU 420 in response to the trigger frame410. However, due to the interference of the PPDU 430 transmitted bySTA2, STA1 may determine that the channel is busy as a result of theCCA-ED. As like above, the UL-MU transmission process of the BSS1 may beinterrupted due to the spatial reuse operation of the inter-BSSterminal.

FIG. 8 illustrates an embodiment of the present invention forrestricting a spatial reuse operation. According to an exemplaryembodiment of the present invention, a spatial reuse operation of aterminal receiving an inter-BSS PPDU 510 containing a trigger frame maybe prohibited until the end of the transmission of the PPDU 510 (S201).According to the embodiment of the present invention, if the inter-BSSPPDU 510 containing the trigger frame is in a predetermined PPDU format,the spatial reuse operation may be prohibited. More specifically, if theinter-BSS PPDU 510 containing the trigger frame is an HE single-user(SU) PPDU or an HE extended range SU PPDU, the spatial reuse operationmay be prohibited. Therefore, a terminal receiving the inter-BSS PPDU510 in the HE SU PPDU or the HE extended range SU PPDU format determinesthat the channel is busy and does not perform the spatial reuseoperation. When the spatial reuse operation is prohibited until the endof transmission of the inter-BSS PPDU 510 containing the trigger frame,it is possible to prevent interference from occurring when STAsindicated by the trigger frame perform carrier sense. According to afurther embodiment of the present invention, not only when the receivedinter-BSS PPDU 510 contains the trigger frame but also when it containsthe predetermined frame or information, the spatial reuse operation ofthe terminal receiving the PPDU 510 may be prohibited until the end ofthe transmission of the PPDU 510 (S201).

Various signaling methods may be used to prohibit the spatial reuseoperation until the end of the transmission of the PPDU 510. Accordingto an embodiment of the present invention, the trigger frame containedin the PPDU 510 may be identified via a type field and/or a subtypefield of a frame control field of the MAC header. Accordingly, when thetype field and/or the subtype field of the frame control field of theMAC header of a frame contained in the inter-BSS PPDU 510 indicates atrigger frame, the terminal receiving the PPDU 510 may not perform thespatial reuse operation.

According to another embodiment of the present invention, informationprohibiting the spatial reuse operation may be signaled through thepreamble of the PPDU 510. For example, when a spatial reuse (SR) fieldof HE-SIG-A of the PPDU 510 is set to a specific value (i.e., the firstvalue), the spatial reuse operation may be prohibited. According to theembodiment of the present invention, when the trigger frame is carriedin an HE SU PPDU or an HE extended range SU PPDU, the SR field ofHE-SIG-A of the corresponding PPDU may be set to the first valueprohibiting the spatial reuse operation. Therefore, when the SR field ofHE-SIG-A of the inter-BSS PPDU 510 is set to the first value prohibitingthe spatial reuse operation, the terminal receiving the PPDU 510 may notperform the spatial reuse operation. In this case, the spatial reuseoperation is prohibited until the end of the transmission of the PPDU510 as described above. The terminal receiving the inter-BSS PPDU 510whose SR field is set to the first value prohibiting the spatial reuseoperation determines that the channel is busy and does not perform thespatial reuse operation. As described above, when the information forprohibiting the spatial reuse operation is signaled through thepreamble, whether or not to perform the spatial reuse operation can bedetermined at an earlier point than the case where the information issignaled through the MAC header.

FIG. 9 illustrates another embodiment of the present invention forrestricting a spatial reuse operation. According to another embodimentof the present invention, a terminal receiving an inter-BSS PPDU 520containing a trigger frame may perform a restricted spatial reuseoperation until the end of the transmission of the PPDU 520 (S202).According to an embodiment of the present invention, if the inter-BSSPPDU 520 containing the trigger frame is in a predetermined PPDU format,the spatial reuse operation may be restricted to be performed within theduration of the PPDU 520. More specifically, if the inter-BSS PPDU 520containing the trigger frame is an HE MU PPDU, the spatial reuseoperation may be restricted to be performed within the duration of thePPDU 520. Therefore, a terminal receiving the inter-BSS PPDU 520 in theHE MU PPDU format may perform the spatial reuse operation only until theend of the transmission of the PPDU 520. If the spatial reuse operationis restricted to be performed within the duration of the inter-BSS PPDU520 containing the trigger frame, it is possible to prevent interferencefrom occurring when STAs indicated by the trigger frame perform carriersense. According to a further embodiment of the present invention, notonly when the received inter-BSS PPDU 510 contains the trigger frame butalso when it contains the predetermined frame or information, thespatial reuse operation of the terminal receiving the PPDU 520 may berestricted to be performed within the duration of the PPDU 520 (S202).

Various signaling methods may be used to restrict the spatial reuseoperation to be performed within the duration of the PPDU 520. Accordingto an embodiment of the present invention, the trigger frame containedin the PPDU 520 may be identified via the type field and/or the subtypefield of the frame control field of the MAC header. Accordingly, whenthe type field and/or the subtype field of the frame control field ofthe MAC header of the frame contained in the inter-BSS PPDU 520indicates a trigger frame, the terminal receiving the PPDU 520 mayperform the spatial reuse operation only until the end of thetransmission of the PPDU 520.

According to another embodiment of the present invention, informationrestricting the spatial reuse operations may be signaled through thepreamble of the PPDU 520. For example, when an SR field of HE-SIG-A ofthe PPDU 520 is set to a specific value (i.e., the second value), thespatial reuse operation may be restricted. According to the embodimentof the present invention, when the trigger frame is carried in an HE MUPPDU, the SR field of HE-SIG-A of the corresponding PPDU may be set tothe second value restricting the spatial reuse operation. Accordingly,when the SR field of HE-SIG-A of the inter-BSS PPDU 520 is set to thesecond value restricting the spatial reuse operation, the terminalreceiving the PPDU 520 may perform the spatial reuse operation onlyuntil the end of the transmission of the PPDU 520. As described above,when the information for restricting the spatial reuse operation issignaled through the preamble, whether or not to perform the spatialreuse operation can be determined at an earlier point than the casewhere the information is signaled through the MAC header.

FIG. 10 illustrates a legacy PPDU containing a trigger frame. The legacyPPDU includes a very high throughput (VHT) PPDU, a high throughput (HT)PPDU, a non-HT PPDU, and a non-HT duplicate PPDU, but the presentinvention is not limited thereto.

The trigger frame may be carried in a legacy PPDU. According to theembodiment of the present invention, in the legacy PPDU, the triggerframe may be transmitted in the form of A-MPDU with which any otherframe is aggregated. However, the trigger frame may be transmitted inthe form of A-MPDU when it is carried in an HT PPDU or a VHT PPDU amonglegacy PPDUs. According to an embodiment, the trigger frame may beaggregated with a multicast data frame to form an A-MPDU and betransmitted through a legacy PPDU. When the trigger frame is transmittedthrough the legacy PPDU, legacy STAs can perform an appropriate deferoperation. In addition, the trigger frame may be aggregated with othertypes of trigger frame, such as an MU-block ACK request (BAR) frame, toform an A-MPDU and be transmitted through the legacy PPDU. When thetrigger frame and any other frame are aggregated to form an A-MPDU, thetrigger frame may be located at the start of the corresponding A-MPDU.Thus, even after the trigger frame is decoded, the duration of the PPDUmay remain by another aggregated frame.

The non-legacy terminal may identify the trigger frame in the legacyPPDU and determine whether the frame is an intra-BSS frame or aninter-BSS frame. More specifically, the non-legacy terminal may identifythe trigger frame based on information of the MAC header of the triggerframe contained in the legacy PPDU. The trigger frame may be identifiedvia a type field and/or a subtype field of the MAC header. Also, thenon-legacy terminal may determine whether the corresponding frame is anintra-BSS frame or an inter-BSS frame based on the information of theMAC header. Whether the frame is an intra-BSS frame or an inter-BSSframe can be determined based on MAC address information of the MACheader. Therefore, the non-legacy terminal that has decoded the triggerframe of the legacy PPDU may identify the corresponding trigger framebased on the information of the MAC header, and determine whether thecorresponding frame is an intra-BSS frame or an inter-BSS frame based onthe information of the MAC header.

According to a further embodiment of the invention, whether the legacyPPDU carries a trigger frame can be identified via a legacy preamble. Inthis case, the legacy preamble may be HT SIG or VHT SIG, but the presentinvention is not limited thereto. For example, whether a trigger frameis carried in the PPDU may be signaled via a particular field of thelegacy preamble. The particular field may be a reserved field of aservice field. According to another embodiment, whether a trigger frameis carried in the PPDU may be signaled via at least one guard subcarrierof the preamble. The non-legacy terminal can identify the trigger framein the legacy PPDU through the signaling information.

FIG. 11 illustrates a non-legacy PPDU containing a trigger frame. Thenon-legacy PPDU include a high efficiency (HE) PPDU, but the inventionis not limited thereto.

The trigger frame may be carried in a non-legacy PPDU. According to theembodiment of the present invention, in the non-legacy PPDU, the triggerframe may be transmitted in the form of A-MPDU with which any otherframe is aggregated. According to an embodiment, the trigger frame maybe aggregated with a multicast data frame to form an A-MPDU and betransmitted through a non-legacy PPDU. When the trigger frame istransmitted through the non-legacy PPDU, new functions of the non-legacywireless LAN system may be additionally used. In addition, the triggerframe may be aggregated with other types of trigger frames, such as anMU-BAR frame, to form an A-MPDU and be transmitted through thenon-legacy PPDU. When the trigger frame and any other frame areaggregated to form an A-MPDU, the trigger frame may be located at thestart of the corresponding A-MPDU. Thus, even after the trigger frame isdecoded, the duration of the PPDU may remain by another aggregatedframe.

The non-legacy terminal may determine whether the non-legacy PPDUcontains an intra-BSS PPDU (i.e., the PPDU is an intra-BSS PPDU) or aninter-BSS frame (i.e., the PPDU is an inter-BSS PPDU) based on one ormore determination conditions. First, the non-legacy terminal maydetermine whether the PPDU contains an intra-BSS frame or an inter-BSSframe based on the BSS color value of HE-SIG-A of the non-legacy PPDU.However, in a BSS color collision situation where different BSSs use thesame BSS color, the non-legacy terminal may perform decoding bymisinterpreting an inter-BSS frame as an intra-BSS frame. In this case,the non-legacy terminal may additionally determine whether the frame isan intra-BSS frame or an inter-BSS frame based on information (e.g., MACaddress) of the MAC header of the MAC frame contained in the PPDU. Ifthe determination based on the BSS color is different from thedetermination based on the MAC address, the non-legacy terminal mayfinally determine whether the PPDU contains an intra-BSS frame or aninter-BSS frame according to the determination based on the MAC address.Also, the non-legacy terminal may identify a trigger frame based oninformation of the MAC header of the trigger frame contained in thenon-legacy PPDU. The trigger frame may be identified via a type fieldand/or a subtype field of the MAC header. Accordingly, the non-legacyterminal that has decoded the trigger frame of the non-legacy PPDU mayidentify the corresponding trigger frame based on the information of theMAC header, and determine whether the corresponding frame is anintra-BSS frame or an inter-BSS frame based on the information of theMAC header.

According to a further embodiment of the present invention, thenon-legacy terminal may determine whether to continue decoding the PPDUbased on a UL/DL field value of HE-SIG-A of the non-legacy PPDU. Forexample, the AP may continue decoding the corresponding PPDU when theUL/DL field of HE-SIG-A of the received PPDU is set to UL. In addition,the non-AP STA may continue decoding the corresponding PPDU when theUL/DL field of HE-SIG-A of the received PPDU is set to DL.

FIG. 12 illustrates a further embodiment of the invention forrestricting a spatial reuse operation. As described above in theembodiments of FIGS. 10 and 11, the non-legacy terminal can identify thetrigger frame in a received PPDU 530 and determine whether the frame isan intra-BSS frame or an inter-BSS frame. In this case, the PPDU 530that the non-legacy terminal can identify and determine includes boththe legacy PPDU and the non-legacy PPDU. If the trigger frame containedin the received PPDU 530 is aggregated with another frame to form anA-MPDU, the duration of the PPDU 530 may remain even after the triggerframe is decoded.

According to the embodiment of the present invention, a terminalreceiving an inter-BSS PPDU 530 containing a trigger frame may berestricted in the spatial reuse operation during the remaining durationR_duration of the PPDU 530. According to an embodiment, if the receivedPPDU 530 is an inter-BSS PPDU and contains a trigger frame, the spatialreuse of the terminal may be prohibited for the remaining durationR_duration of the PPDU 530. In this case, the terminal determines thatthe channel is busy and does not perform the spatial reuse. According toanother embodiment, if the received PPDU 530 is an inter-BSS PPDU andcontains a trigger frame, the terminal may perform a restricted spatialreuse operation for the remaining duration R_duration of the PPDU 530.That is, the spatial reuse operation of the terminal is restricted to beperformed within the remaining duration R_duration of the PPDU 530. Byrestricting the spatial reuse operation as described above, it ispossible to prevent interference from occurring when STAs indicated bythe trigger frame perform carrier sense.

According to a further embodiment of the present invention, therestriction of the spatial reuse operation described above can beperformed conditionally. More specifically, the terminal receiving theinter-BSS PPDU 530 containing the trigger frame may adjust the spatialreuse operation depending on whether the remaining duration R_durationof the PPDU 530 is greater than a predetermined threshold SR_thr. If theremaining duration R_duration of the PPDU 530 is greater than thepredetermined threshold SR_thr, the terminal may perform the restrictedspatial reuse operation for the remaining duration R_duration of thePPDU 530. However, if the remaining duration R_duration of the PPDU 530is less than the predetermined threshold SR_thr, the spatial reuse ofthe terminal may be prohibited for the remaining duration R_duration ofthe PPDU 530.

FIG. 13 illustrates a spatial reuse operation according to an embodimentof the present invention. As described above in the embodiments of FIGS.10 and 11, the non-legacy terminal can identify the trigger frame in areceived PPDU and determine whether the frame is an intra-BSS frame oran inter-BSS frame. When the spatial reuse operation for the inter-BSSPPDU containing the trigger frame is restricted in accordance with theembodiment of the present invention, it is possible to preventinterference from occurring when STAs that intend to transmit atrigger-based PPDU perform carrier sense. According to the embodiment ofthe present invention, such a frame protection can be performed not onlyfor the trigger frame but also for an ACK corresponding to the UL-MUtransmission. More specifically, in a manner as described in theembodiment of FIG. 8, the SR field of HE-SIG-A of the PPDU containingthe ACK may be set to the first value prohibiting the spatial reuseoperation. Further, in a manner similar to that described in theembodiments of FIGS. 10 and 11, an ACK frame contained in the PPDU canbe identified. In this case, the spatial reuse operation of a terminalreceiving the inter-BSS PPDU containing the ACK may be prohibited untilthe transmission of the corresponding PPDU is completed. Alternatively,in a manner as described in the embodiment of FIG. 9, the SR field ofHE-SIG-A of the PPDU containing the ACK may be set to the second valuerestricting the spatial reuse operation. Further, in a manner similar tothat described in the embodiments of FIGS. 10 and 11, an ACK framecontained in the PPDU can be identified. In this case, the spatial reuseoperation of a terminal receiving the inter-BSS PPDU containing the ACKmay be restricted to be performed within the duration of thecorresponding PPDU.

HE MU PPDU of Inter-BSS

FIG. 14 illustrates an HE MU PPDU format according to an embodiment ofthe present invention. Referring to FIG. 14, the HE MU PPDU may containa legacy preamble and a non-legacy preamble. The legacy preambleincludes L-STF, L-LTF and L-SIG. The non-legacy preamble of the HE MUPPDU includes RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF and HE-LTF.

The HE-SIG-A of the HE MU PPDU contains a UL/DL field. The UL/DL fieldindicates the transmission direction of the corresponding PPDU. That is,the field indicates whether the corresponding PPDU is transmitted via anuplink or transmitted via a downlink. The HE-SIG-B field is present inthe HE MU PPDU and is transmitted in units of 20 MHz. In addition, theHE-SIG-B field indicates information necessary for receiving the HE MUPPDU. As will be described later in the embodiment of FIG. 15, theHE-SIG-B consists of a common block field and a user specific field.

FIG. 15 illustrates an encoding structure and transmission method of anHE-SIG-B according to an embodiment of the present invention. FIG. 15(a)illustrates the encoding structure of HE-SIG-B, and FIG. 15(b)illustrates the transmission method of HE-SIG-B in a bandwidth of 40 MHzor more.

Referring to FIG. 15(a), the HE-SIG-B consists of a common block fieldand a user specific field. First, the common block field contains aresource unit (RU) allocation field. The RU allocation field containsinformation on resource unit allocation of a specific bandwidth (e.g.,20 MHz) in the frequency domain. More specifically, the RU allocationfield is configured in units of 8 bits and indexes the size of theresource units constituting the specific bandwidth and their placementin the frequency domain. In addition, the RU allocation field mayindicate the number of users in each resource unit. When the totalbandwidth through which the PPDU is transmitted is greater than apredetermined bandwidth (e.g., 40 MHz), the RU allocation field may beset to a multiple of 8 bits to carry information in units of thespecific bandwidth.

On the other hand, the user specific field consists of a plurality ofuser fields, and carries information for a STA designated to eachallocated resource unit. Each user field of the user specific field isarranged in order of allocated users in the resource unit arrangementindicated by the RU allocation field of the common block field. Aplurality of user fields are transmitted in units of a user block field.The user block field is made up of an aggregation of two user fields, aCRC field and a tail field. Depending on the total number of userfields, the last user block field may contain information for one or twoSTAs. For example, if a total of three users (i.e., STA1, STA, and STA3)are designated, information for STA1 and STA2 is coded and transmittedalong with the CRC/tail field in the first user block field, andinformation for STA3 may be coded and transmitted along with theCRC/tail field in the last user block field. That is, if the totalnumber of user fields is odd, the last user block field may contain oneuser field. At the end of the HE-SIG-B, padding may be added along theOFDM symbol boundary.

Each user field contains an STA-ID field, and the STA-ID field indicatesan AID of the receiver of the corresponding resource unit.Exceptionally, when the HE MU PPDU is used for an uplink transmission,the STA-ID field may indicate an AID of the transmitter. When one useris allocated to one resource unit (i.e., non-MU-MIMO allocation), theuser field may contain a number of spatial streams (NSTS) field, atransmit beamforming (TxBF) field, a modulation and coding scheme (MCS)field, a dual sub-carrier modulation (DCM) field and a coding field. Onthe other hand, when a plurality of users are allocated to one resourceunit (i.e., MU-MIMO allocation), the user field contains a spaceconfiguration field (SCF), an MCS field, a DCM field and a coding field.

Referring to FIG. 15(b), HE-SIG-B is separately encoded on each 20 MHzband. In this case, the HE-SIG-B may consist of a maximum of twocontents in units of 20 MHz, that is, an HE-SIG-B content channel 1 andan HE-SIG-B content channel 2. In the embodiment of FIG. 15(b), each boxrepresents a 20 MHz band, and “1” and “2” in the boxes represent theHE-SIG-B content channel 1 and the HE-SIG-B content channel 2,respectively. Each HE-SIG-B content channel in the total band isarranged in order of the physical frequency band. That is, the HE-SIG-Bcontent channel 1 is transmitted in the lowest frequency band, and theHE-SIG-B content channel 2 is transmitted in the next higher frequencyband. Such a content channel configuration is then duplicated throughcontent duplication in the next higher frequency bands. For example, forthe first to fourth channels with an increasing order of the frequencyconstituting the entire 80 MHz band, the HE-SIG-B content channel 1 istransmitted on the first channel and the third channel, and the HE-SIG-Bcontent channel 2 is transmitted on the second channel and the fourthchannel. Likewise, for the first to eighth channels with an increasingorder of the frequency constituting the entire 160 MHz band, theHE-SIG-B content channel 1 is transmitted on the first channel, thethird channel, the fifth channel and the seventh channel, and theHE-SIG-B content channel 2 is transmitted on the second channel, thefourth channel, the sixth channel and the eighth channel. When theterminal can decode the HE-SIG-B content channel 1 through at least onechannel and decode the HE-SIG-B content channel 2 through the other atleast one channel, information on the MU PPDU configuration of the totalbandwidth can be obtained. On the other hand, when the total bandwidthis 20 MHz, only one SIG-B content channel is transmitted.

According to the embodiment of the present invention, when the HE MUPPDU is transmitted via an uplink, the STA-ID field of each user fieldof the HE-SIG-B of the corresponding PPDU may indicate an AID of thetransmitter. That is, when the UL/DL field in the HE-SIG-A of the HE MUPPDU is set to UL, the STA-ID field of each user field in the HE-SIG-Bof the corresponding PPDU indicates the AID of the transmitter. Sincethe recipient of the HE MU PPDU transmitted via an uplink is an AP, itis possible to support the spatial reuse operation by allowing theSTA-ID field of the user field of the corresponding PPDU to indicate theAID of the transmitter.

According to a further embodiment of the present invention, theconfiguration of the HE-SIG-B may be adjusted to reduce the overhead ofthe HE-SIG-B when the HE MU PPDU is transmitted via an uplink. Forexample, the resource unit allocation field of HE-SIG-B may be expressedin the form of the resource unit allocation field of the trigger frame.In addition, the user specific field of HE-SIG-B may contain a userfield only for one user. In addition, the HE-SIG-B contents in each 20MHz band may be set equal to each other.

FIG. 16 illustrates a method for determining an intra-BSS frame and aninter-BSS frame according to a further embodiment of the presentinvention. As described above, the terminal may determine whether a PPDU610 contains an intra-BSS frames (i.e., the PPDU is an intra-BSS PPDU)or an inter-BSS frame (i.e., the PPDU is an inter-BSS PPDU) based on oneor more determination conditions. However, in a BSS color collisionsituation where different BSSs use the same BSS color, the terminal mayperform decoding by misinterpreting an inter-BSS frame as an intra-BSSframe. In this case, the terminal may determine whether the PPDU 610contains an intra-BSS frame or an inter-BSS frame by considering otherconditions for intra/inter-BSS determination.

FIG. 16 illustrates an intra/inter-BSS determination procedure when anAP receives an HE MU PPDU 610 transmitted via an uplink. In theembodiment of FIG. 16, it is assumed that the PPDU 610 received by theAP is a PPDU transmitted from other BSS using the same BSS color as theBSS of the AP. First, the AP receives the PPDU 610 (S301). The AP maydetermine whether the PPDU 610 contains an intra-BSS frame or aninter-BSS frame based on preamble information of the PPDU 610. If thePPDU 610 is an HE MU PPDU, the preamble of the PPDU 610 containsHE-SIG-A and HE-SIG-B.

First, the AP decodes the HE-SIG-A of the PPDU 610 and performsintra/inter-BSS determination based on information of the decodedHE-SIG-A (S302). More specifically, the AP determines whether the PPDU610 contains an intra-BSS frame or an inter-BSS frame based on theinformation of the BSS color field in the HE-SIG-A of the PPDU 610. Asdescribed above, if the BSS color of the PPDU 610 is equal to the BSScolor of the BSS of the AP, the AP determines that the PPDU 610 containsan intra-BSS frame. However, if the BSS color of the PPDU 610 is notequal to the BSS color of the BSS of the AP, the AP determines that thePPDU 610 contains an inter-BSS frame. Since the BSS color collisionoccurs in the embodiment of FIG. 16, the AP may determine that the PPDU610 contains an intra-BSS frame in step S302. Thus, the AP continuesdecoding the PPDU 610. Meanwhile, the AP may identify that the UL/DLfield is set to UL in the decoding process of the HE-SIG-A of the PPDU610.

Next, the AP decodes the HE-SIG-B of the PPDU 610 and performsintra/inter-BSS determination based on information of the decodedHE-SIG-B (S303). More specifically, the AP determines whether the PPDU610 contains an intra-BSS frame or an inter-BSS frame based on theinformation of the user specific field of the HE-SIG-B of the PPDU 610.As described above, if the PPDU 610 is an HE MU PPDU transmitted via anuplink, the STA-ID field of the user field in the HE-SIG-B of the PPDU610 indicates an AID of the transmitter. Accordingly, if the AIDindicated by the user field of the HE-SIG-B in the PPDU 610 contains avalue that is not assigned in the BSS of the AP, the AP determines thatthe PPDU 610 contains an inter-BSS frame.

As described above, according to the embodiment of the presentinvention, one or more conditions can be used for intra/inter-BSSdetermination of the PPDU 610. For example, the AP may determine whetherthe PPDU 610 contains an intra-BSS frame or an inter-BSS frame based onat least one of the information of the BSS color field in the HE-SIG-Aof the PPDU 610 and the information of the user specific field in theHE-SIG-B of the PPDU 610. Moreover, the AP may determine whether thePPDU 610 contains an intra-BSS frame or an inter-BSS frame based on atleast one of the information of the user specific field in the HE-SIG-Bof the PPDU 610 and the information of the MAC address field of the MACframe contained in the PPDU 610. However, determination results may bedifferent in two or more intra/inter-BSS determination conditions amongthe above listed conditions. That is, the received PPDU 610 may satisfyboth the intra-BSS determination condition and the inter-BSSdetermination condition. According to the embodiment of the presentinvention, when the PPDU 610 satisfies both the intra-BSS condition andthe inter-BSS condition, the determination based on the user field ofthe HE-SIG-B may take precedence over the determination based on the BSScolor field of the HE-SIG-A. Further, the determination based on the MACaddress field may take precedence over the determination based on theuser specific field of HE-SIG-B.

The AP may perform either the first operation or the second operationdistinct from each other according to the final result of theintra/inter-BSS determination. That is, when it is determined that thePPDU 610 contains an intra-BSS frame, the AP may perform the firstoperation. Specific embodiments of the first operation are as describedabove. Meanwhile, when it is determined that the PPDU 620 contains aninter-BSS frame, the AP may perform the second operation. According tothe embodiment of the present invention, the second operation may be aspatial reuse operation, and specific embodiments thereof are asdescribed above.

FIG. 17 illustrates an embodiment for transmitting an HE MU PPDU via anuplink and setting a NAV accordingly. In the embodiment of FIG. 17, APand STA1 are terminals of the first BSS (e.g., BSS1), and STA2 is aterminal of the second BSS (e.g., BSS2). As shown in FIG. 17(a), STA1transmits an uplink HE MU PPDU to the AP.

Referring to FIG. 17(b), the STA may transmit data using some of theresource units among all available resource units when transmitting theHE MU PPDU. For example, the STA may perform uplink data transmission ona specific resource unit using the HE MU PPDU in order to transmit datathrough a resource unit with better channel conditions. Alternatively,the STA may perform uplink data transmission on a specific resource unitusing the HE MU PPDU in order to transmit data with avoiding theresource units already occupied. According to an embodiment of thepresent invention, the STA may transmit the HE MU PPDU using a resourceunit that does not include the primary 20 MHz channel of the BSS withwhich the STA is associated.

According to the embodiment of the present invention, even if data ofthe HE MU PPDU is transmitted via the uplink using only some resourceunits, the STA may transmit the preamble of the PPDU on a 20 MHz, 40MHz, 80 MHz or 160 MHz (80+80 MHz) channel including the correspondingresource unit according to the conventional channel bonding rules. Inthis manner, the probability that the AP succeeds in receiving the HE MUPPDU may increase, and the intra-BSS STAs may perform the correct deferoperation.

Referring to FIG. 17(a), the HE MU PPDU transmitted by STA1 of BSS1 maybe received by STA2 of BSS2 which is another BSS. STA2 may decode theHE-SIG-A of the PPDU transmitted by the STA1 and identify that the PPDUcontains an inter-BSS frame, is an HE MU PPDU, and is transmitted viathe uplink. Also, STA2 may decode the HE-SIG-B of the PPDU and identifythe location of the resource unit on which data of the PPDU is to betransmitted. According to the embodiment of the present invention, whenit is determined, as a result of decoding the HE-SIG-B of the inter-BSSPPDU, that the resource unit on which the data of the PPDU is to betransmitted is not included in the primary 20 MHz channel of the BSSwith which STA2 is associated, STA2 may not set and update a NAV.Accordingly, STA2 can use the unoccupied channel, and the spatial reuseperformance can be improved. According to another embodiment of thepresent invention, when it is determined, as a result of decoding theHE-SIG-B of the inter-BSS PPDU, that the resource unit on which the dataof the PPDU is to be transmitted is not included in the primary 20 MHzchannel of the BSS with which STA2 is associated, STA2 may set or updatea NAV only until the preamble portion of the corresponding PPDU(alternatively, may determine as a CCA busy state).

FIG. 18 illustrates another embodiment of transmitting an HE MU PPDU viaan uplink. In the embodiment of FIG. 18, duplicative description ofparts which are the same or corresponding to the aforementionedembodiment of FIG. 17 will be omitted.

As shown in FIG. 18, when an uplink transmission using the HE MU PPDU isperformed through an 160 MHz channel or an 80+80 MHz channel, terminalsof the inter-BSS receiving the PPDU cannot identify which 80 MHz channelthe location of the resource unit indicated by the resource unitallocation field of the HE-SIG-B of the PPDU corresponds to.Accordingly, the STAs of the inter-BSS receiving the PPDU cannotidentify whether the resource unit included in the primary 20 MHzchannel of the BSS with which the STA is associated is to be used fordata transmission. Therefore, according to the embodiment of the presentinvention, when the HE MU PPDU is transmitted via an uplink, only theresource units included in the primary 80 MHz channel may be used.

Transmission Opportunity (TXOP) Duration

FIG. 19 illustrates an HE PPDU format according to an embodiment of thepresent invention. Referring to FIG. 19, the HE PPDU may contain alegacy preamble, a non-legacy preamble, data and a packet extension (PE)field. The legacy preamble includes L-STF, L-LTF and L-SIG. Thenon-legacy preamble includes RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF andHE-LTF. In this case, the HE-SIG-B may be contained only in a specificPPDU format, for example, an HE MU PPDU.

The L-SIG field contains a length field indicating the length of thecorresponding PPDU. The length field of the L-SIG consists of 12 bits,and may be referred to as an L_Length field in the embodiment of thepresent invention. The HE-SIG-A field contains a TXOP duration fieldindicating the length of the TXOP. According to an embodiment, the TXOPduration field may consist of 7 bits. Also, the data field may contain aMAC frame, and the MAC header of the MAC frame contains a duration (orduration/ID) field. The duration field of the MAC header indicates thelength of the TXOP and may consist of 15 bits. According to theembodiment of the present invention, the HE PPDU may have two or morefields, each consisting of a different number of bits, indicating alength. That is, the HE PPDU may contain a duration field of the MACheader and a TXOP duration field which consist of a different number ofbits with each other.

Hereinafter, various embodiments of the method of setting andinterpreting the TXOP duration field will be described with reference tothe respective drawings. The STA sets or updates a NAV based on the TXOPduration value of the TXOP duration field in the HE-SIG-A of the HEPPDU. According to an embodiment of the present invention, a TXOPduration value is obtained from the TXOP duration field, and theobtained value may indicate a duration after the HE-SIG-A field in whichthe TXOP duration field is present. In this case, a STA receiving the HEPPDU may set or update a NAV without further calculation on the obtainedTXOP duration value even when it suspends decoding after the HE-SIG-A ofthe corresponding PPDU. According to another embodiment of the presentinvention, the TXOP duration value obtained from the TXOP duration fieldmay indicate a duration after the end of the corresponding PPDU. In thiscase, the TXOP duration field may not incorporate the valuecorresponding to the length of the corresponding PPDU in the TXOPduration value. Thus, a wider range of TXOP duration values can berepresented by the limited number of bits of the TXOP duration field. Inthis case, a STA receiving the HE PPDU may set or update a NAV based onthe sum of the TXOP duration value obtained from the TXOP duration fieldand the length of the corresponding PPDU.

According to an embodiment of the present invention, the TXOP durationfield may represent the TXOP duration value in units of OFDM symbolduration. Therefore, the TXOP duration value TXOP_V may be determinedbased on Equation 1 below.TXOP_V=TXOP_D*symbol_D  [Equation 1]

In Equation 1, TXOP_D denotes the value of the TXOP duration field, andsymbol_D denotes the symbol duration. That is, the TXOP duration valuemay be determined based on the value obtained by multiplying the valueof the TXOP duration field and the symbol duration. According to anembodiment, the symbol duration may be set to a symbol length 13.6 us towhich the basic cyclic prefix (CP) 0.8 us is added. According to anotherembodiment, the symbol duration may be set to 16 us to represent a widerrange of TXOP. A STA receiving the HE PPDU sets or updates a NAV basedon the thus obtained TXOP duration value.

FIG. 20 illustrates another embodiment of a method of setting andinterpreting a TXOP duration field. According to another embodiment ofthe present invention, the TXOP duration field may contain a first bitfield indicating the length of the TXOP and a second bit fieldindicating the granularity of the TXOP length.

FIG. 20(a) illustrates an embodiment in which the TXOP duration fieldconsisting of 7 bits contains a first bit field consisting of 5 bits anda second bit field consisting of 2 bits. Referring to FIG. 20(b), thesecond bit field of the TXOP duration field may index predeterminedgranularity information. For example, in the second bit field, the fieldvalue ‘00’ may indicate 4 us, the field value ‘01’ may indicate Bus, thefield value ‘10’ may indicate 16 us, and the field value ‘11’ mayindicate 32 us. In this case, the TXOP duration value TXOP_V may bedetermined based on Equation 2 below.TXOP_V=TXOP_L*TXOP_G  [Equation 2]

In Equation 2, TXOP_L denotes the value (i.e., the length of the TXOP)of the first bit field of the TXOP duration field, and TXOP_G denotesthe value (i.e., the granularity of the TXOP length) of the second bitfield of the TXOP duration field. That is, the TXOP duration value isdetermined based on the value obtained by multiplying the length of theTXOP obtained from the first bit field of the TXOP duration field andthe granularity of the TXOP length obtained from the second bit field ofthe TXOP duration field. In the embodiment of FIG. 20, the first bitfield and the second bit field of the TXOP duration field consist of 5bits and 2 bits, respectively, but the present invention is not limitedthereto. According to another embodiment of the present invention, thefirst bit field and the second bit field of the TXOP duration field mayconsist of 6 bits and 1 bit, respectively, and the size of each bitfield may be modified according to the embodiment. A STA receiving theHE PPDU sets or updates a NAV based on the thus obtained TXOP durationvalue.

FIG. 21 illustrates yet another embodiment of a method of setting andinterpreting the TXOP duration field. According to yet anotherembodiment of the present invention, the TXOP duration value may beobtained using both the value obtained from the TXOP duration field andthe value of the L_Length field of L-SIG. For example, the TXOP durationvalue TXOP_V may be calculated based on Equation 3 below.TXOP_V=L_Length_V*TXOP_FV  [Equation 3]

In Equation 3, L_Length_V denotes the value of the L_Length field ofL-SIG, and TXOP_FV denotes the value obtained from the TXOP durationfield. That is, the TXOP duration value is determined based on the valueobtained by multiplying the value obtained from the TXOP duration fieldand the value of the L_Length field. In this case, the value L_Length_Vof the L_Length field may be a value converted in units of time.

According to the embodiment of the present invention, the TXOP durationfield may represent various values using the floating-pointrepresentation method. Referring to FIG. 21, the TXOP duration field maycontain a third bit field indicating a fractional value and a fourth bitfield indicating an exponent value. In this case, the value TXOP_FVobtained from the TXOP duration field may be expressed by Equation 4below.TXOP_FV=(1+TXOP_Frac)*2{circumflex over ( )}(TXOP_Exp−bias)  [Equation4]

In Equation 4, TXOP_Frac denotes the value (i.e., fractional value) ofthe third bit field of the TXOP duration field, and TXOP_Exp denotes thevalue (i.e., exponent value) of the fourth bit field of the TXOPduration field. If the TXOP duration field consists of n bits and thethird bit field thereof consists of n_f bits, the fourth bit may consistof n-n_f bits. In this case, TXOP_Frac may be calculated by Equation 5below.

$\begin{matrix}{{TXOP\_ Frac} = {\sum\limits_{k = 0}^{{n\_ f} - 1}{{B(k)}*{2\hat{}\left( {k - {n\_ f}} \right)}}}} & \left\lbrack {{Equation}5} \right\rbrack\end{matrix}$

In Equation 5, B(k) denotes the value of the bit k of the TXOP durationfield. That is, TXOP_Frac is determined by adding the value ofB(k)*2{circumflex over ( )}(k−n_f) until k becomes from 0 to n_f−1. InEquation 4, TXOP_Exp may be any value from 0 to 2{circumflex over( )}(n-n_f)−1, which indicates the value of the fourth bit field of theTXOP duration field in decimal. Further, in Equation 4, the bias may be2{circumflex over ( )}(n-n_f−1)−1. That is, when n is 7 and n_f is 3 asin the embodiment shown in FIG. 21, the bias may be 7. On the otherhand, when the TXOP_V obtained according to the embodiment of FIG. 21 isnot an integer, the TXOP duration value may be determined by roundingup, rounding down, or rounding off TXOP_V in units of us.

FIG. 22 illustrates still another embodiment of a method of setting andinterpreting a TXOP duration field. According to still anotherembodiment of the present invention, the granularity of the valueindicated by the TXOP duration field may be different depending on thetype of the PPDU. Therefore, the TXOP duration value TXOP_V may bedetermined based on Equation 6 below.TXOP_V=TXOP_D*G_PPDU  [Equation 6]

In Equation 6, TXOP_D denotes the value of the TXOP duration field, andG_PPDU denotes the predetermined granularity of the TXOP durationaccording to the type of the PPDU. That is, the TXOP duration value maybe determined based on the value obtained by multiplying the value ofthe TXOP duration field and the granularity according to the type of thePPDU.

FIG. 22 illustrates an example of the predetermined granularityaccording to the type of the HE PPDU. Referring to FIG. 22, thegranularity of the TXOP duration of the MU PPDU or the trigger-basedPPDU may be set to a value larger than the granularity of the TXOPduration of the SU PPDU or the extended range SU PPDU. The transmissionand exchange sequence of the MU PPDU is likely to require a longer TXOPthan the transmission of the SU PPDU. Thus, an MU PPDU may use a TXOPduration granularity that is larger than that of an SU PPDU. As shown inFIG. 22, the TXOP duration field of the SU PPDU and/or the extendedrange SU PPDU may indicate a TXOP duration with a granularity of a shortsymbol length 13.6 us and the TXOP duration field of the MU PPDU and/orthe trigger-based PPDU may indicate a TXOP with a granularity of a longsymbol length 16 us, but the present invention is not limited thereto.

According to a further embodiment of the present invention, thegranularity of the TXOP duration may be determined by additionallyreflecting the CP length used for the corresponding PPDU. For example,if a CP of 0.8 us is used for the PPDU, the granularity of the TXOPduration may be (12.8+0.8) us. The CP length used for the PPDU isobtained from a subfield of HE-SIG-A.

FIGS. 23 and 24 illustrate additional embodiments for setting andupdating the NAV based on the TXOP duration value. According to anembodiment of the present invention, the TXOP duration field may notcover the entire TXOP length to be protected. According to theembodiment of FIG. 23, the TXOP duration field may indicate a TXOPduration value up to the transmission completion time of the next PPDU.Also, according to the embodiment of FIG. 24, the TXOP duration fieldmay indicate a TXOP duration value up to the transmission completiontime of the next of the next PPDU. However, when the sequences of PPDUsare transmitted within the TXOP, STA1 of the BSS receiving the sequencesof PPDUs may continuously set and update a NAV based on the TXOPduration field of the received PPDUs. Thus, the entire sequence of thePPDUs transmitted during the TXOP period can be protected.

Although the present invention is described by using the wireless LANcommunication as an example, the present invention is not limitedthereto and the present invention may be similarly applied even to othercommunication systems such as cellular communication, and the like.Further, the method, the apparatus, and the system of the presentinvention are described in association with the specific embodiments,but some or all of the components and operations of the presentinvention may be implemented by using a computer system having universalhardware architecture.

The detailed described embodiments of the present invention may beimplemented by various means. For example, the embodiments of thepresent invention may be implemented by a hardware, a firmware, asoftware, or a combination thereof.

In case of the hardware implementation, the method according to theembodiments of the present invention may be implemented by one or moreof Application Specific Integrated Circuits (ASICSs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, micro-controllers, micro-processors,and the like.

In case of the firmware implementation or the software implementation,the method according to the embodiments of the present invention may beimplemented by a module, a procedure, a function, or the like whichperforms the operations described above. Software codes may be stored ina memory and operated by a processor. The processor may be equipped withthe memory internally or externally and the memory may exchange datawith the processor by various publicly known means.

The description of the present invention is used for exemplification andthose skilled in the art will be able to understand that the presentinvention can be easily modified to other detailed forms withoutchanging the technical idea or an essential feature thereof. Thus, it isto be appreciated that the embodiments described above are intended tobe illustrative in every sense, and not restrictive. For example, eachcomponent described as a single type may be implemented to bedistributed and similarly, components described to be distributed mayalso be implemented in an associated form.

The scope of the present invention is represented by the claims to bedescribed below rather than the detailed description, and it is to beinterpreted that the meaning and scope of the claims and all the changesor modified forms derived from the equivalents thereof come within thescope of the present invention.

INDUSTRIAL APPLICABILITY

Various exemplary embodiments of the present invention have beendescribed with reference to an IEEE 802.11 system, but the presentinvention is not limited thereto and the present invention can beapplied to various types of mobile communication apparatus, mobilecommunication system, and the like.

The invention claimed is:
 1. A wireless communication terminal, theterminal comprising: a processor; and a communication unit, wherein theprocessor is configured to: receive a PHY protocol data unit (PPDU), andclassify the PPDU into an inter-BSS PPDU or an intra-BSS PPDU accordingto an intra-BSS condition or an inter-BSS condition, wherein whethereach of the inter-BSS condition or the intra-BSS condition is satisfiedis determined based on a BSS color of a BSS color field included in aHE-SIG-A when the HE-SIG-A of the PPDU includes the BSS color field, andwherein whether the PPDU is the intra-BSS PPDU or the inter-BSS PPDU isclassified by a condition of a MAC address among the intra-BSS conditionand the inter-BSS condition when the PPDU is identified as the inter-BSSPPDU according to the inter-BSS condition and is identified as theintra-BSS PPDU according to the intra-BSS condition, respectively. 2.The wireless communication terminal of claim 1, wherein the intra-BSScondition is used to determine whether the PPDU is the intra-BSS PPDU,and wherein the inter-BSS condition is used to determine whether thePPDU is the inter-BSS PPDU.
 3. The wireless communication terminal ofclaim 1, wherein whether the inter-BSS condition is satisfied isdetermined based on a high efficiency(HE)-signal(SIG)-B of the PPDU,when the PPDU is an HE multi-user (MU) PPDU.
 4. The wirelesscommunication terminal of claim 1, wherein whether the PPDU is aninter-BSS PPDU or an intra-BSS PPDU is classified based on whether avalue related to an association identifier(AID) included in the PPDUequals to a value assigned by a BSS associated with the base wirelesscommunication terminal, when whether each the inter-BSS condition andthe intra-BSS condition is satisfied is based on a value related to theAID included in the PPDU.
 5. The wireless communication terminal ofclaim 1, wherein the inter-BSS condition is based on information of aMAC address field of a MAC frame contained in the PPDU, wherein theintra-BSS condition is based on a BSS color of a BSS color fieldincluded in a HE-SIG-A, and wherein the PPDU is determined to includethe inter-BSS frame according to the information of the MAC addressfield of the MAC frame when the PPDU satisfies both the inter-BSScondition by the information of the MAC address field of the MAC frameand the intra-BSS condition by the BSS color of the BSS color fieldincluded in the HE-SIG-A.
 6. A wireless communication method of awireless communication terminal, the method comprising: receiving a PHYprotocol data unit (PPDU); and classifying the PPDU into an inter-BSSPPDU or an intra-BSS PPDU according to an intra-BSS condition or aninter-BSS condition, wherein whether each of the inter-BSS condition orthe intra-BSS condition is satisfied is determined based on a BSS colorof a BSS color field included in a HE-SIG-A when the HE-SIG-A of thePPDU includes the BSS color field, and wherein whether the PPDU is theintra-BSS PPDU or the inter-BSS PPDU is classified by a condition of aMAC address among the intra-BSS condition and the inter-BSS conditionwhen the PPDU is identified as the inter-BSS PPDU according to theinter-BSS condition and is identified as the intra-BSS PPDU according tothe intra-BSS condition, respectively.
 7. The wireless communicationmethod of claim 6, wherein the intra-BSS condition is used to determinewhether the PPDU is the intra-BSS PPDU, and wherein the inter-BSScondition is used to determine whether the PPDU is the inter-BSS PPDU.8. The wireless communication method of claim 6, wherein whether theinter-BSS condition is satisfied is determined based on a highefficiency(HE)-signal(SIG)-B of the PPDU, when the PPDU is an HEmulti-user (MU) PPDU.
 9. The wireless communication method of claim 6,wherein whether the PPDU is an inter-BSS PPDU or an intra-BSS PPDU isclassified based on whether a value related to an associationidentifier(AID) included in the PPDU equals to a value assigned by a BSSassociated with the base wireless communication terminal, when whethereach the inter-BSS condition and the intra-BSS condition is satisfied isbased on a value related to the AID included in the PPDU.
 10. Thewireless communication method of claim 6, wherein the inter-BSScondition is based on information of a MAC address field of a MAC framecontained in the PPDU, wherein the intra-BSS condition is based on a BSScolor of a BSS color field included in a HE-SIG-A, and wherein the PPDUis determined to include the inter-BSS frame according to theinformation of the MAC address field of the MAC frame when the PPDUsatisfies both the inter-BSS condition by the information of the MACaddress field of the MAC frame and the intra-BSS condition by the BSScolor of the BSS color field included in the HE-SIG-A.